下面是我的代码，我正在尝试从 sqlite 数据库中检索数据，并从用户输入的文本字段中查询机场城市名称，并检索要在标签中显示的 ICAO 标识符。似乎数据库正在加载，但当我选择 IBAction 按钮时它不会查询。我认为我的查询语句或数据库可能有问题，尽管我不能在这里列出。任何帮助将不胜感激。
我收到的最后一个错误是：database3[30351:c07] -[ViewController searchICAO:] 1st SQL error 'library routine called out of sequence' (21)
-(NSString*)filePath {
NSArray*paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
return [[paths objectAtIndex:0]stringByAppendingPathComponent:@"mydatabase.sqlite"];
}
//open database
- (void)viewDidLoad{
[self openDB];
}
-(void)openDB {
if(sqlite3_open([[self filePath]UTF8String], &airportDB) !=SQLITE_OK) {
sqlite3_close(airportDB);
NSAssert(0, @"Databese failed to open");
status.text = @"Database Failed to Open";
}
else if (sqlite3_open([[self filePath]UTF8String], &airportDB) ==SQLITE_OK) {//this line not really needed but was trying everything
NSLog(@"database opened"); //test
status.text = @"Database Opened"; //test
}
}
- (IBAction)searchICAO:(id)sender
{
//[self.delegate detailViewControllerDidFinish:self]; //for later use
//Get airport name from the text field user enters
NSString*sql = [NSString stringWithFormat:@"SELECT * FROM airports WHERE city=\"%@\"", [searchDB text]];
const char *query_stmt = [sql UTF8String];
sqlite3_stmt *statement;
NSLog(@"%s 1st SQL error '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(airportDB), sqlite3_errcode(airportDB)); //Error Test
这是我似乎遇到问题的地方......
if (sqlite3_prepare_v2(airportDB, query_stmt, -1, &statement, NULL)==SQLITE_OK) {// Problem is from here, can't get past this point
NSLog(@"%s 2nd SQL error '%s' (%1d)", __FUNCTION__, sqlite3_errmsg(airportDB), sqlite3_errcode(airportDB)); //Error Test
if (sqlite3_step(statement)==SQLITE_ROW) {
status.text = @""; //Clear the status line
NSString *returnICAO = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement, 1)];
status.text = returnICAO; //Insert Airport ICAO letters from the database table
}
sqlite3_finalize(statement);
[super viewDidLoad];
}
sqlite3_close(airportDB);
}